Technical Field
The present disclosure is directed to a method of setting a waveform signal in an apparatus for ultrasound applications and an apparatus for generating ultrasounds using such method.
The present disclosure is directed to a method and a device that are configured to generate an ultrasonic waveform signal (hereinafter briefly referred to as acoustic signal) for use in an apparatus for ultrasound applications.
Description of the Related Art
An apparatus for ultrasound applications is, for instance, an ultrasound or sonographic machine that may comprise a medical diagnostic testing system that uses ultrasonic waves or ultrasounds and is based on the principle of ultrasound transmission and echo emission analysis. Such apparatuses are widely used in internal medicine, surgery and radiology.
In such machine, the acoustic signal is directed to a target region, for example, in the human body, for 2D or 3D scanning, and when the acoustic signal impinges upon such region, the apparatus receives the reflected acoustic signal and processes it to generate the 2D/3D image on a screen.
It shall be noted that the present disclosure also applies to any system that may be used to acquire an arbitrary waveform signal. This signal may be of analog type, converted by a transducer into an analog electrical signal and then converted by an n-bit ADC (Analog-to-Digital Converter) into n digital electrical signals, before being acquired by recording, otherwise it may be directly of digital electrical type. The signal so recorded and stored may be used to control actuators for ultrasound applications, not necessarily piezoelectric actuators, but also optical, mechanical or other types of actuators, as used in contexts such as telecommunications or industrial automation.
A variety of types of integrated circuits (ASIC) are known in the art, which facilitate configuration, delaying and generation of distinct acoustic signals for use in an ultrasound imaging apparatus.
For example, referring to FIG. 1, which shows a block diagram of an integrated circuit for use in a prior art apparatus for ultrasound applications, an interface 1 is shown, which receives a waveform signal WF with a preset duration TWF and is in signal communication with a first functional block 2, that acts as a unit for generating an acoustic signal profile, and with a second functional block 3 that is in signal communication with both the functional block 2 and the interface 1 and acts as a unit for setting phase delays of the acoustic signal.
Acoustic signals are generated through a plurality of transducer elements 5, which are configured to transmit their respective acoustic signals to the selected target region and to later receive the reflected acoustic signal.
It may be further noted that the device comprises a third functional block 4, which is in signal communication with the second block 2 and acts as a waveform pulse generator, and with a plurality of transducers 5, each receiving the pulse of the acoustic signal to be generated from said third functional block 4.
For example, the interface 1 is a serial interface and uses an appropriate data transmission protocol to transfer the bits 2A to configure the acoustic signal profile to the functional block 2 and the bits 2B for setting phase delays to the functional block 3.
The functional block 3 receives the acoustic signal profile generated by the block 2, replicates it for each transducer and associates a phase delay with each copy.
Each of these signals is emitted through the functional block 4 to its respective transducer 5.
Two approaches are used to store the waveforms to be generated. The first approach uses a first serial communication to store the basic waveforms containing a single state, the time during which such state remains, and a relative index. Then, it uses a second serial communication to store a sequence of indices describing the sequence of basic waveforms that form the entire waveform.
This system provides good versatility but requires additional information (the sequence of indices), which involves higher area usage and two communication operations with the serial interface that require longer setup times.
For example, in order to store the waveform of FIG. 6A, 2 bits will be required to describe one of the 4 states, 3 bits will be required to store the state maintenance time (8 units max) and 4 bits will be required to associate an index with the 13 basic waveforms. As a whole, the storage of this simple waveform will require (2+3+4)×13=117 bits. The second approach consists in storing the parameters that describe the waveform as a whole, e.g., the number and duration of pulses. This system affect flexibility in waveform configuration to prevent excessive memory usage, and hence excessive area usage.
For example, a maximum number of pulses will be limited to Ni, and configuration will be limited to the durations of the first and last pulses, and an identical duration for all the others, the sequence of states being fixed to a given non-configurable sequence.
Obviously, storage limited to simple waveforms like the ones of FIG. 4 can be stored, and waveforms like that of FIG. 6A cannot be stored.
It will be understood that, with the clock frequencies that are usually employed in these systems, e.g., from 50 to 200 MegaHertz, the time required for transfer of the bits required to set the profile and the phase delays becomes a significant consideration.
This is even truer when considering the need of setting different acoustic signal profiles.
Indeed, as the number of acoustic signal profiles employed for scanning increases, a longer time is needed to configure the system by setting all the descriptive parameters of the different waveforms in use.
This is due to the need of storing the profile of the acoustic signal to be emitted.
For example, in a system with 200 MHz clock, 177 flip-flops would be used to store the profile of an acoustic signal like that of FIG. 6A, having a duration of 115 nsec. In the first prior art approach the time for configuration includes two serial communications with a header time imposed by the selected profile. These operations are used to fill both the actually employed 117 flip-flops and, for the purpose of configuration of the whole system and compliance with the selected protocol, possibly also unused flip-flops.
The minimum time will be: Tconf=117×5 ns+2×Theader.
It shall be noted that the possibility of having a wide choice in setting different profiles and acoustic signal delays will afford a higher accuracy of the images of the object to be scanned.